Increasing, gene-therapy strategies are pursued for the treatment of tumor diseases. It is hereby often of interest to express the therapeutic gene for a defined period of time in a sufficient quantity in the target cells and let it become effective for tumor therapy. For this reason, promoters that are inducible by way of defined, therapy-associated modalities, are important for the construction of conditionally active vectors in gene therapy. Vectors that can be regulated by a specific therapy enable a controlled expression of the therapeutic gene (Walther 1996, Mol. Biotechnol. 6: 267-86).
The invention has the objective of regulating the tumor gene therapy through therapeutic modalities, such as chemotherapy or hyperthermia, for the period of these therapies, so that the gene therapy, together with chemotherapy, hyperthermia, and other means, results in a controlled, more efficient treatment of the tumor disease.
The objective of the invention is realized by using an expression vector according to claim 1. Secondary claims characterize the vector according to the invention in more detail. An essential characteristic is a vector that is characterized by a therapy-inducible LRP/MVP promoter or a defined sequence thereof and by a gene encoding for a therapeutically relevant protein. This promoter is inducible by chemotherapy, hyperthermia, and other means, and in this way permits the therapy-induced expression of subsequent therapeutic genes. Therapeutically relevant proteins include cytokines, enzymes, antibodies, apoptosis genes, resistance genes. anti-oncogenes, tumor necrosis factor alpha, interferon alpha, interferon gamma, interleukin 2, interleukin 6, interleukin 7, interleukin 12, GM-CSF, G-CSF, herpes simplex thymidine kinase. cytosine deaminase, nitroreductase, and cytochrome P-450.
It was unexpectedly found that the human LRP/MVP gene promoter isolated and cloned by the inventors is inducible through therapy-relevant factors, and the expression of subsequent genes thus can be controlled. These inductors include chemotherapy agents, such as cisplatin, 5-fluoruracil, adriamycin, vincristin etc., but also other therapy-associated factors, such as, for example, hyperthermia and irradiation. The vector of the invention according to Claim 1 therefore enables the cytostatic- and/or hyperthermia-induced expression of therapeutic genes in the target cells (tumor cells), and therefore a combination of gene therapy and chemotherapy, hyperthermia, and/or irradiation.
As a base structure for the vectors according to the invention, all constructs suitable for expression in mammalian cells can be used. These include vector base structures based on DNA (for example, adenoviruses, AAV) or RNA viral vectors (for example, MoMuLV, HIV). The vectors according to the invention therefore can be introduced into the target cells with suitable non-viral (gene gun, liposomes, electroporation) or viral carrier systems and unfold the therapeutic effect. The therapeutic effect of the vector according to the invention is created in that, after the vector transfer by chemotherapy, hyperthermia, or irradiation, the expression of the therapeutic gene is induced by the LRP/MVP promoter, and the resulting antitumor gene products are released in the tumor cell and, as the case may be, in its environment. With the help of the invention, the combination of gene therapy (antitumor effects of the induced therapeutic genes) and chemotherapy, hyperthermia, and/or irradiation is able to result in improved tumor therapy.
The invention is described in more detail using the following embodiments: